89

0900 5 Feb

Plotter did not work properly
with program that worked previously.
Only command that it seemed to
get was to raise & lower pen.

Don Pieper

DITTO Raj Reddy

0910

The power switch on the QI Control
unit is broken.

J. Gleason

1415

Tested the plotter and found that ddrum
up-down operation and the carriage left-right operation
was working very erratically. The only thing that was
working was the pen up-down command. We first
tried to use the paper tape punch, since it uses
the same I/O channel. It worked fine. Need we
tested the cable between the 166 and the Cal Comp
platter for continuity and shorts. It was okay also. (The
wiring list for this cable has been entered on the PTP Control-761
drawing and in the Hardware Notes book.) We finally
discovered that the input pulses from the PTP driver
that drive the plotter were marginal; i.e. when the
amplitude was dropped by ~ 2% the plotter stopped!
The attenuators on the output of the PTP driver have
been changed to double the pulse height going into the
plotter. The plotter was then tested with the petal program
and seems to work okay.

Old Circuit [diagram] New Circuit [diagram]

J. Gleason